Water- Conductivity 0/ the Wood in Trees and Shrubs. 229 



Table V. — Huscus aculeatus. Eight stems, of which seven are divided into a 



lower and upper half. 



Absolute vol. in c.c. 

 per J hour. 



Specific vol. in c.c. 

 per i hour. 



Average. 



Entire 

 r Lower 

 \ Upper 



{Lower 

 Upper 

 f Lower 

 \ Upper 

 f Lower 

 \ Upper 



{Lower 

 Upper 

 f Lower 

 1 Upper 

 r Lower 

 1 Upper 



0-2 



0-2 



0-1 



0-3 



0-2 



0-15 



0-15 



0-2 



0-1 



0-15 



0-15 



0-2 



1 



0-2 



0-2 



77 

 76 

 49 

 15 

 96 

 81 

 04 

 85 

 78 

 75 

 78 

 10 

 74 

 85 

 12 



Mean 



= -86 

 (nearly) 



the material at my disposal, the stems of which were about 0"4 cm. in 

 diameter. Although very much greater than that of its shrubby relatives, 

 its conductivity still falls far below that of the common dicotyledonous 

 climbers. It is probable that the rather clumsy and characteristic appear- 

 ance of most arborescent monocotyledons is to be associated with a defective 

 water conductivity. The Palms, for example, commonly have leathery leaves 

 and unbranched stems. There are, however, some exceptions amongst the 

 palms, and it would be of great interest to know more about the efficiency of 

 their wood. 



Among dicotyledonous climbers the Ivy deserves notice, since it illustrates 

 a feature that is very characteristic of climbers in general. The wood of its 

 creeping youth-form has a low conductivity value, ranging round 25, but as 

 the plant reaches the freely branching large-leaved adult form (" Tree Ivy "), 

 the vascular tissue undergoes a change, and the conductivity increases to at 

 least twice the value of that characteristic of the juvenile stage. But the 

 relatively inadequate water supply is seen in the inability of the plant to 

 succeed in exposed dry situations, and by the reduction in the size of its 

 leaves plainly to be observed in Ivy that is freely open to sun and wind. 



The common Privet {Ligustrum vulgare) stands high among the evergreens 

 as regards conductivity. It often sheds its leaves in winter, and may, 

 therefore, be regarded as approaching the deciduous class. Its principal 

 range, as determined from an examination of 50 stems, extends from 30 to 42, 



